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Polyethylene glycol promotes autoxidation of cytochrome c

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Title: Polyethylene glycol promotes autoxidation of cytochrome c
Authors: Sato, Wataru Browse this author
Uchida, Takeshi Browse this author →KAKEN DB
Saio, Tomohide Browse this author
Ishimori, Koichiro Browse this author →KAKEN DB
Keywords: Heme
Cytochrome c
Electron transfer
Issue Date: Jun-2018
Publisher: Elsevier
Journal Title: Biochimica et Biophysica Acta (BBA) - General Subjects
Volume: 1862
Issue: 6
Start Page: 1339
End Page: 1349
Publisher DOI: 10.1016/j.bbagen.2018.03.010
Abstract: Cytochrome c (Cyt c) was rapidly oxidized by molecular oxygen in the presence, but not absence of PEG. The redox potential of heme c was determined by the potentiometric titration to be +236 ± 3 mV in the absence of PEG, which was negatively shifted to +200 ± 4 mV in the presence of PEG. The underlying the rapid oxidation was explored by examining the structural changes in Cyt c in the presence of PEG using UV–visible absorption, circular dichroism, resonance Raman, and fluorescence spectroscopies. These spectroscopic analyses suggested that heme oxidation was induced by a modest tertiary structural change accompanied by a slight shift in the heme position (<1.0 Å) rather than by partial denaturation, as is observed in the presence of cardiolipin. The near-infrared spectra showed that PEG induced dehydration from Cyt c, which triggered heme displacement. The primary dehydration site was estimated to be around surface-exposed hydrophobic residues near the heme center: Ile81 and Val83. These findings and our previous studies, which showed that hydrated water molecules around Ile81 and Val83 are expelled when Cyt c forms a complex with CcO, proposed that dehydration of these residues is functionally significant to electron transfer from Cyt c to CcO.
Rights: © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license
Type: article (author version)
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 内田 毅

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